<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .bottom {
            width: 100%;
            height: 335px;
            background-color: antiquewhite;
        }
        #ss1 {
            margin: 0 auto;
            width: 1300px;
            height: 335px;
            background-color:aquamarine;
        }
        #a1 {
            height: 100%;
            background-color: black;
        }
    </style>
</head>
<body>
    <div class="bottom">
        <div id="a1"></div>
        <div id="ss1"></div>
    </div>
</body>
</html>